Police are spending £6 million a year fulfilling their obligations to inquests and inquiries related to historic Troubles killings.

The bill covers staff costs for the PSNI's legacy support unit, computer systems to document old case files and reports, and legal fees, according to Deputy Chief Constable Judith Gillespie.

The senior officer outlined the expenditure as she updated the Policing Board on the latest developments in the inquests into the so-called shoot-to-kill deaths.

The police have been involved in a lengthy legal wrangle with Northern Ireland's Senior Coroner John Leckey over the disclosure of the top secret Stalker/Sampson reports into the six security force killings almost 30 years ago.

An agreement has now been reached which will see Mr Leckey review the documents to decide which parts are relevant to the inquests before the police then assess what information will need to be redacted for security reasons.

But Mrs Gillespie said a substantial financial outlay would still be needed to cover police costs for those inquests and other historic cases. "This ruling doesn't really affect the resources because it is still going to require considerable resources to deal with the legacy issues," she said.

"Alone the staff costs in the legacy support unit are over £1 million per year and there is also significant capital expenditure on IT and legal fees so broadly speaking our current assessment is that around £6 million per year will be spent on the legacy inquests and the legacy inquiries.

"But that is very much a moving feast because it very much depends on the complexity of the particular legacy inquest, the legal fees involved and the searching of the relevant documents."

There are more than 30 such inquests relating to Troubles killings that have yet to be heard. In regard to the shoot-to-kill incidents, police had been concerned that they would have had to redact all the Stalker/Sampson documentation before Mr Leckey began the exercise of deciding relevance - an exercise officers believe could have taken years.

Mrs Gillespie welcomed the agreement over relevance. "Now that clarity has been provided, which we very much welcome, we have invited the senior coroner to commence that process by coming in and seeing all of the material and deciding what is relevant and once he has seen all the material and decided what's relevant that will allow us then to review the material to fulfil our Article Two (Human Rights Act - Right to Life) obligations."